Surgical device and method

ABSTRACT

A surgical device  20  for attaching staples  40  to a portion of a body comprising an anvil  23 ; a smart memory material (SMM)  50, 75  capable of going from one physical state to another physical state; a supply of staples in communication with the smart memory material and placed near the anvil; and an activating apparatus  21  which is in communication with the smart memory material and which can cause the change in the physical state of the smart memory material, which change in state causes the movement of the staples against the anvil thereby securing the staples  40  to the desired body portion. The device utilizes a source of electricity which when activated causes the SMM to expand in volume thereby moving an individual staple from the supply of staples. The device may also contain a surgical knife  62  to cut a body portion wherein a SMM is in communication with the knife whereby when the SMM expands it engages the knife causing the knife to cut the desired body portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.10/366,170, filed Feb. 13, 2003, which is a continuation-in-partapplication to U.S. patent application Ser. No. 10/348,087 filed Jan.20, 2003, all hereby incorporated by reference.

FIELD OF THE INVENTION

The invention pertains to a surgical device for attaching staples to aportion of a body. The invention also pertains to a surgical device forcutting a portion of a body.

The invention also pertains to smart memory materials that can changefrom one physical phase to another physical phase upon application of astimulus and the use of those materials in a surgical device.

BACKGROUND OF THE INVENTION

Medical stapling devices for endoscopic or laparoscopic surgery employvery complex mechanisms. Frequently, the devices rely on a set of cambars and the like to eject the surgical staples from the staplecartridge. (See U.S. Pat. No. 3,499,591.) Complex linkages containedwithin the body of the device are used to articulate the staplecartridge and an anvil into position during the surgical procedure. (SeeU.S. Pat. No. 6,250,532.) The range of motion, flexibility and size ofsuch stapling devices are restricted by these mechanisms. Examples ofcomplicated apparatus for applying surgical staples to attach an objectto body tissue is described in U.S. Pat. Pub. 2002/0117534, publishedAug. 29, 2002. The apparatus requires complex mechanical actuatingmechanisms for rotating and articulating the surgical device and then tocause the staple to be ejected from a store of staples. A flexibleconnection (fire wire) with a high level of fatigue life is neededbetween the push rod and the pusher plate at the pivot point of thearticulated joint. In a similar fashion, see U.S. Pat. No. 6,250,532.The devices described in the patents contain complex linkages to ejectthe staples from the staple cartridge/magazine limiting therange-of-motion for the articulated end of the device. In some of thedevices, cam bars are used to deploy the staples. The ability of the cambars to deflect or flex is limited to approximately +/−45° of movement.Additional, when operating at the extremes of this travel, early fatiguefailure of the cam bars is possible.

The power required to actuate the device of the invention disclosedherein is supplied to the staple cartridge through very small andflexible wires. Because of the small size and flexibility, the requiredspace and packaging requirements are significantly less in comparison tothe cam bars described in the patents of the prior art.

Polymeric materials having smart memory characteristics are described in“Shape Memory Polymers”: A. Yondlen, S. Kelch Angen, Chem Int. Ed. 2002,41(12), pp. 2034-2057. The use of smart memory materials is discussed inU.S. Pat. No. 5,509,923. See also U.S. Pat. No. 6,388,043, hereinincorporated by reference.

An apparatus for endoscopically applying body staples to body tissue isdescribed in U.S. Pat. No. 5,484,095.

Other patents which are generally related to surgical devices or smartmemory materials are recited below. ISSUED/ PATENT NO./ PUBLISHEDPUBLICATION NO. APPL'N. DATE U.S. 5,236,437* Aug. 17, 1993 U.S.5,242,458 Sept. 7, 1993 U.S. 5,411,519 May 2, 1995 U.S. 5,431,323* July11, 1995 U.S. 5,467,911 Nov. 21, 1995 U.S. 5,484,095 Jan. 16, 1996 U.S.5,509,923 Apr. 23, 1996 U.S. 5,636,780 June 10, 1997 U.S. 5,645,209 Jul.8, 1997 U.S. 5,681,330 Oct. 28, 1997 U.S. 5,711,472 Jan. 27, 1998 U.S.5,797,959 Aug. 25, 1998 U.S. 5,810,881 Sept. 22, 1998 U.S. 6,019,758Frb. 1, 2000 U.S. 6,159,146 December 12, 2000 U.S. 6,250,531 B1 June 26,2001 U.S. Pub. 2001/0007057 A1 Pub. Jul. 5, 2001 U.S. Pub. 2001/0030219A1 Pub. Oct. 18, 2001 U.S. Pub. 2002/0072759 1 Pub. June 13, 2002 U.S.Pub. 2002/0096550 1 Pub. Jul. 25, 2002 U.S. Pub. 2002/0117534 A1 Pub.Aug. 29, 2002 U.S. 6,488,196 B1 Dec. 3, 2002

It is an object of the present invention to utilize a surgical devicefor attaching staples to a portion of a body by employing a smart memorymaterial capable of going from one physical state to another physicalstate by means of an activating apparatus which is in communication withthe smart memory material and which can cause the phase change whichphase change causes movement of the staples against an anvil therebysecuring the staples to the desired body portion.

It is also an object of the present invention to facilitate a method ofattaching staples to a body portion utilizing the aforementionedsurgical device.

It is also an object of the present invention to employ a surgicaldevice for cutting a portion of a body where the surgical device has aknife that is capable of moving from a first to a second position whichpositions are spaced apart and to utilize a smart memory material whichfunctions as described above; namely, utilizing an activating apparatuswhich is a communication with the smart memory material and by virtue ofthe change in the physical state can cause the movement of the knifethereby facilitating the cutting of the desired body portion.

It is also an object of the present invention to describe a method ofperforming a surgical operation employing the above-described surgicaldevice for cutting a portion of the body.

It is also an object of the present invention to utilize theabove-described surgical device for attaching staples which device alsohas the capability of cutting a portion of the body utilizing thecombination of staples and knife by utilizing the combination of thesurgical devices described above.

It is also an object of the present invention to perform a surgicaloperation utilizing the combined surgical device for stapling andcutting a portion of a body.

SUMMARY OF THE INVENTION

Described is a surgical device for attaching staples to a portion of abody comprising an anvil; a smart memory material (SMM) capable of goingfrom one physical state to another physical state; a supply of staplesin communication with the smart memory material and placed near theanvil; and an activating apparatus which is in communication with thesmart memory material and which can cause the change in the physicalstate of the smart memory material, which change in state causes themovement of the staples against the anvil thereby securing the staplesto the desired body portion.

The surgical device may also employ a knife for cutting a portion of abody comprising a knife capable of moving from a first position to asecond position which is spaced apart from the first position; a smartmemory material (SMM) capable of going from one physical state toanother physical state; and an activating apparatus which is incommunication with the smart memory material and which can cause thechange in the physical state of the smart memory material, which changein state causes the movement of the knife thereby facilitating cuttingof the desired body portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of the surgical device of the present invention.

FIG. 2 is a side-sectional view of the surgical device of the presentinvention showing movement of the anvil in an open phantom view.

FIG. 3 is a side-sectional view of the surgical device of the presentinvention showing the smart memory material aligned with a store ofstaples.

FIG. 4 is a schematic view of the surgical device of the presentinvention in a ready state.

FIG. 5 is a schematic view of the surgical device of the presentinvention in an engaged state depicting the attachment of the staplesand movement of the surgical knife.

FIG. 6 is a side-sectional view of one embodiment of the surgical deviceof the present invention in the ready state.

FIG. 6A is a side-sectional view of one embodiment in the engaged state;namely, the staples are secured towards the anvil.

FIG. 7 is a side-sectional view of the surgical device of the presentinvention depicting the surgical knife in a recessed area.

FIG. 8 is a side-sectional view of the surgical device of the presentinvention showing the surgical knife in an engaged position, out of therecessed area.

FIG. 9 is a side-sectional view of a second embodiment of the surgicaldevice of the present invention in a ready state.

FIG. 10 is a side-sectional view of the second embodiment of thesurgical device of the present invention in an engaged view with thestaples secured.

FIG. 11 is a sectional view through lines 11-11 of FIG. 3.

FIG. 12 is a sectional view along the lines 12-12 of FIG. 3.

An alternative embodiment of the invention is shown in FIGS. 13-15 and17-19.

FIG. 13 is a side-sectional view of an alternative embodiment of thepresent invention.

FIG. 14 is a side-sectional view of an alternative embodiment of thepresent invention wherein the surgical knife is in a first positionprior to a surgical cutting operation.

FIG. 15 is a side-sectional view of an alternative embodiment of thepresent invention wherein the surgical knife is in a second positionfrom the first position of FIG. 14 wherein the surgical knife has movedfrom the first position to the second position.

FIG. 16 is another embodiment of the invention.

FIG. 17 is a sectional view taken along the lines 17-17 of FIG. 13.

FIG. 18 is a sectional view taken along the lines 18-18 of FIG. 13.

FIG. 19 is a perspective view of a wedge with surgical knife utilized inthe present invention.

FIG. 20 is an alternative embodiment of the wedge with surgical knifeutilized in the present invention.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Smart memory material (SMM) means a material or composition that canmove from a first to a second physical state and then back to itsdesired original physical state by activation or stimuli. The change instate may result in an increase in volume of the SMM.

An “activating apparatus” means an apparatus that can stimulate the SMMthereby changing the state. The stimuli can be the application of heatand/or electrical current to SMM or some other mechanism that caneffectuate the change in physical state. One example of physical statechange is going from a martensite phase to an austenite phase.

The application of smart memory material can simplify a surgicalstapling device into four basic components: a staple cartridge, an anvilfor staple closure, an energy/power source (remote or local) and aswitch/trigger (remote or local). The staple cartridge contains thesurgical staple, a surgical blade and a SMM actuator/driver. Theactuator/driver is used to drive the surgical staple from the cartridge,through the tissue and into contact with the anvil to initiate closureof the staples. The actuator/driver is also used to drive the surgicalblade to create an incision in the tissue. The energy/power source is tosupply the thermal energy or magnetic field to elicit a response of thesmart materials actuator/driver and is triggered by the switch.

The flexibility of this concept provides several advantages over currentdevices as follows:

-   -   Staple actuator/driver can be located in the staple cartridge        with staple    -   Surgical blade and actuator/driver may be incorporated in staple        cartridge    -   Staple cartridge and anvil may be affixed to any device/handle        for positioning during procedure    -   Staple cartridge and anvil mechanism may be adapted to        endoscopic or laparoscopic surgical procedures    -   Staple cartridge is not limited in length by a mechanical        actuation device    -   The staple cartridge may be of various cross sections to fit the        surgical application    -   The surgical device may work with any form or size staple    -   Staple cartridge may contain one, two, . . . to n staples in        one, two, . . . n rows    -   Staple cartridge may be configured to staple in linear,        circular, concave, convex, parabolic or zigzag patterns, and the        like    -   The device facilitates driving individual staples from the        staple cartridge sequentially, alternately and any combination        thereof, and the like    -   The device facilitates driving multiple staples or sets of        staples in one operation    -   The device facilitates driving sets of staples from a staple        cartridge in a variety of configurations: single, multiple or        alternating rows    -   The device may be utilized to tack surgical incisions

The surgical device herein is designed in such a way that it may beattached to any type of handle or device to articulate/manipulate itsposition and/or orientation. If the handle or device has the ability toarticulate +/−180° (yaw) and rotate 360°, the desired development can bearticulate through these extremes. This is possible because of thesimplicity of the interface between the staple cartridge and thehandle/device. The interface need only contain a method to hold thestaple cartridge and an electrical connector. The electrical connectorcan be nothing more than electrical contains that are engaged by thestaple cartridge when it is attached to the handle/device. Theelectrical connector is used to supply a voltage via small wires fromthe switch which is connected to the energy source. The electricalconnector, integral to the staple cartridge, connects to the SMMcontained in the cartridge to eject the staple when the voltage issupplied via the switch.

In the various embodiments, similar components use the same referencenumerals.

For a first embodiment FIGS. 1 and 2 show the top sectional and sidecross section of one embodiment for a surgical (stapling) device 20. Thesurgical (stapling) device 20 has an energy source 21, contained in thebody 27 of the device, a switch 22 that triggers the energy source, ananvil 23, a handle 26 to actuate the anvil 23 and a staple-actuatorcartridge 24. There is also upper cover 33 and lower cover 35.

The handle 26 is pivoted about pin 25. The anvil 23 pivots about pin 28and is connected to the handle 26 by pin 29, which rides in a slot 30 inthe body 27. As handle 26 is rotated from the opened (FIG. 2) to theclosed position (FIGS. 1 and 3), the anvil 23 is then rotated from anopen position to a closed position to clamp tissue (not shown) betweenthe surface of the anvil 23 and the upper surface 31 of thestaple-actuator cartridge 24.

The energy source 21, in a generic sense, is any source of power thatinitiates or elicits a response in a smart memory material. Examples arenot limited to but include a voltage being applied directly to SMM tocreate a current that generates heat, a voltage being applied to a coilto generate heat or a magnetic field to stimulate the smart memorymaterial. The energy source may also encompass any electrical, fluid,magnetic or chemical reaction that can be used to elicit a response froma smart memory material. The energy source may be a heating or coolingsource.

In the staple-actuator cartridge 24, there is a plurality of staples 40contained in a plurality of slots 41, as shown in FIGS. 6 and 6A. Theplurality of staples 40 may be configured in single row or parallel rows(not shown). In the staple-actuator cartridge 24, a plurality of staples40 are located in a plurality of slots 41 against the forward walls 42and aft walls 43 of slots 41. The forward walls 42 and aft walls 43 act,as guides for staples 40 and pushers 49. The staples 40 are located inthe downward position 44 against upper surface 45 of pushers 49. Theplurality of pushers 49, is generally equivalent to the number of slots41 and plurality of staples 40 having grooves in which a driver 50 iscontained. The driver 50 is formed from smart memory material, for theembodiment shown in FIGS. 6, 6A and runs from the forward end 51 of thestaple-actuator cartridge 24 to the aft end 52 of the staple-actuatorcartridge 24. The SMM driver 50 is attached to the energy source 21 atconnector 46.

FIGS. 4 and 5 show a block diagram for the control logic for theembodiment in FIGS. 6 and 6A.

When switch 22 is moved from the neutral position to the forwardposition, the energy source 21 will apply a voltage to the driver 50.The voltage in this instance can only be applied after the safetyinterlock(s) 51 are closed. As the voltage passes into driver 50, theresistance of the smart memory material will begin to generate heat. Asthe heat (energy) increases, the smart memory material will begin to gointo a phase change such as from martensite to austenite. As this phasechange occurs, driver 50 will begin to contract, causing the pluralityof pushers 49 to move upward. As the plurality of pushers 49 move upwardthe plurality of staples 40 will begin to be ejected from thestaple-actuator cartridge 24 and make contact with anvil 23. As driver50 continues to contact, a force sufficient to completely drive theplurality staples 40 from the staple-actuator cartridge 24 and againstanvil 23 to cause the plurality staples 40 to deform into their closedposition 41 as shown in FIGS. 5 and 6A, securing the tissue (not shown).By closed position is meant that the legs of the staple are crimped,preferably together in slots 61 securely fastening the tissue to itselfor to a mesh or substrate (not shown).

Contained in the staple-actuator cartridge 24, are driver 60, pusher 61and surgical blade 62 as shown in FIGS. 5, 7 and 8. When switch 22 ismoved from the forward position through the neutral position into therearward position, the energy source 21 will apply a voltage to driver60. The voltage in this instance preferably is applied after the safetyinterlock indicating completed staple ejection is closed. As the voltagepasses into driver 60, the resistance of the smart memory material willbegin to generate heat. As the heat (energy) increases, the smart memorymaterial will begin to go into a phase change from martensite toaustenite. As this phase change occurs, driver 60 will begin tocontract, causing pusher 61 to move upward. As driver 60 continues tocontract, sufficient force is generated to drive pusher 61 upward, inturn driving surgical blade 62 into its upwardmost position as shown inFIG. 8. As the surgical blade 62 is driven upward, it can make anincision into the tissue between the rows of staples.

An alternative embodiment is shown in FIGS. 9 and 10. In thestaple-actuator cartridge 24, there is a plurality of staples 40contained in a plurality of slots 41. From this point forward in thisembodiment, the device will be described in the singular since forclarification.

In the staple-actuator cartridge 24, the staple 40 is located in slot 41against the forward wall 70 and aft wall 71. Staple 40 is located in thedownward position 72. The SMM driver 75 is folded in such a way as toform an “S” shaped forward leg 76 and aft leg 77. The driver 75 istrapped between staple 40, the reaction surface 80, forward wall 70 andaft wall 71. When the energy source 21 applies a voltage (energy) to thedriver 75, forward leg 76 and aft leg 77 will expand. As forward leg 76and aft leg 77 expand, the upper segment (in the shape of a bar) 78 ofthe driver 75 reacts against the bottom leg 81 of staple 40 and reactionsurface 80. As the forward leg 76 and aft leg 77 expand, the forward end82 and aft end 83 of upper bar 78 are guided by the forward wall 70 andaft wall 71 of staple-actuator cartridge 24. As the forward leg 76 andaft leg 77 expand, the staple 40 is moved linearly until it contacts thesurface of the anvil 23 to initiate closure of the staple 40. Theforward leg 76 and aft leg 77 expand until staple 40 is ejected fromstaple-actuator cartridge 24 and forward staple leg 85 and aft stapleleg 86 are fully closed or crimped as shown in FIG. 10, securing thetissue and/or mesh or substrate (not shown).

The surgical stapling device can be configured to eject the staples fromthe staple-actuator cartridge individually or in any combination. Asolid-state logic controller in the stapling device handle canfacilitate this feature which one of ordinary skill in the art canassemble.

It is to be appreciated that the staple-actuator cartridge is notlimited to linear forms. Because of the flexibility of the smartmaterial (i.e., shape memory alloys and shape memory polymers), thestaple-actuator cartridge can take on any form: circular, concave,convex, parabolic, zigzag or the like. The cross sectional shape of thestaple-actuator cartridge can also be tailored to meet the surgicalneed.

Another embodiment of the present invention is that depicted in FIGS.13-15.

The surgical device 100 has handle 106 and anvil 102. The devicecontains the energy source 108 which is connected to the SMM material110 retained within assembly 112 having a top portion 114 and a bottomportion 116. The anvil 102 has an extension portion 118 that isengagement with the SMM material 110. As the SMM material moves, theanvil 102 moves upward when viewing FIG. 13 causing arm 120 to rotateupward.

In the embodiment depicted in FIG. 13, a surgical blade 122 is attachedto or a portion of a wedge 124 (best shown in FIG. 19) which hasattached thereto the SMM material 110. The wedge has angled surface 126to indicate the initiation of action. The wedge has a bottom surface 128and a back side surface 130 which forms approximately a 90° angle attheir juncture 132. The wedge 124 has a top portion 134, a front portion136 and side 138. Side 138 as can be seen from FIG. 19 is substantiallysmaller than back side portion 130 reflecting the angled surface 126from the back portion 134 to the front surface 136. The wedge 124 has agroove 138 which rides a “T” shaped track. The wedge slides on the trackduring the cutting operation of the blade. In a resting or firstposition, the blade 122 is positioned at the front portion 140 of thesurgical device which may take any configuration but is shown as asemicircular configuration for ease of insertion into the body portionfor ease of handling during a clinical operation. The surgical device100 has a bottom portion 142. The SMM material 110 can be secured to thewedge 124 by any convenient mechanism such as by adhesion and the like,with or without the use of heat or other securing method.

The surgical device 100 has a wedge receiving section 150 in which topportion 152 receives the blade 122 and bottom portion 154 which receiveswedge segment 124. The blade receiving slot 153 is shown in FIG. 17.

As the wedge 124 moves from the position on the right as shown in FIG.13 to the end section 150, the front portion of the wedge surfaces 136 &126 initiation movement against pushers 160 and therefore against thestaples 162 and against the bottom surface 164 of the anvil therebyengaging body tissue. After the staples engage the tissue, the blade 122will cut the tissue.

FIGS. 14 and 15 are further details of the surgical device of FIG. 13.FIG. 14 indicates that the surgical knife 122 is on the right portion ofthe apparatus of the surgical device where the SMM material 110A iscircled about pulley 170 which rotates about pivot point 104. Thesurgical knife moves from the right to the left as shown in FIG. 15where the surgical knife 122 fits into the receiving segment 152. As thesurgical knife moves from the right to the left portion of the surgicaldevice, the SMM material 110A goes from a linear position as shown inFIG. 14 to a curled position 174 in FIG. 15. In other words, by theapplication of heat the SMM material goes from a linear mode as depictedin FIG. 14 into a more curled position where the curl is in segment 176of the FIG. 15. The operation of FIGS. 13-15 indicates that one SMMmaterial 110 operates the anvil to an open or closed position. Anotheror different SMM material 110A activates the movement of the surgicalknife from the right portion of FIG. 14 to the left portion of FIG. 15.While it is expected that these would be two separate operable SMMmaterials, it is obvious to one of skill in the art that the materialscan be lengthened and there could be separate segments that would havethe ability to operate both actions namely the movement of the anvil andthe movement of the blade. For convenience, the electrical connectionsof FIGS. 13-15 are not supplied in detail but would be clear to one ofskill in the art.

FIG. 16 is a schematic view of another alternative of the presentinvention. The surgical device 100 of FIG. 16 is an alternativeembodiment of the operation of the wedge 124 and surgical knife 122. InFIG. 16, the heating mechanism 108 is attached to the SMM 110A. Theembodiment shown in FIG. 16, however, does not have the pulleyarrangement as shown in FIG. 15. In the embodiment of FIG. 16, thesurgical knife moves from the right portion of the surgical device 100to the left portion of the surgical device stopping at receivingposition 150. The action of the SMM is primarily retained in thehorizontal plane of the surgical device 100 without the SMM going arounda pulley. In the embodiment of FIG. 16, the SMM is primarily in alinearly fashion and during the movement from one phase to another. TheSMM can collect in a retaining box 180 in FIG. 16.

FIG. 20 is an alternative embodiment of the wedge with surgical knifeutilized in the present invention.

The wedge 200 is comprised of sloping surfaces 202A and 202B. FIG. 20 iscomprised of FIG. 20A which is a perspective view of the wedge utilizedin the present invention. FIG. 20B is a view of FIG. 20A from the back.FIG. 20C is a view of FIG. 20A from the front and FIG. 20D is aninterior view of FIG. 20A showing the attachment of the SMM to theinterior portion of the wedge.

The wedge has exterior side surface 204 of bottom surface 206 andinterior surface 208 exterior surfaces are 204A and 204B. The surgicalknife has a cutting edge 210 and a back portion 212. Extension 214 ofthe blade likewise has angles for movement of the wedge when it comes incontact with the pushers for movement of the staples. The angle forsurface 214 is comparable to that for surfaces 202A and B. The SMM 220is attached to the interior surface 208A and B of the extension 214 ofthe surgical knife. The wedge 200 has a front lip 230.

It is to be appreciated that the surgical device utilizing its smartmemory material need not utilize the knife portion. In that case, thestapling device can operate as described herein. Alternatively, thesurgical device need not utilize the staple portion. In which case theknife portion may be utilized as described herein. Preferably, however,the knife and stapling mechanism are utilized together as shown.

The driver for ejecting the staples from the staple-actuator cartridgeis not limited to smart memory alloy materials. A smart memory polymercan also provide the actuating force and displacement. Some smart memorymaterials include Nitinol (an acronym for Nickel Titanium Naval OrdnanceLaboratory) which is a family of intermetallic materials, which containa nearly equal mixture of nickel (about 55 wt. %) and titanium. Some ofthose alloy compositions are superelastic materials such as alloy N, Sand C and others are actuator materials, such as alloy B, M, H andFlexinol (trademark of Nitinol Devices and Components for nickeltitanium intermetallic alloys).

Nitinol exhibits unique behavior. The two terms used to describe thisbehavior are “Shape Memory” and “Superelasticity”.

SHAPE MEMORY: Shape memory effect describes the process of restoring theoriginal shape of a plastically deformed sample by heating it. This is aresult of a crystalline phase change known as “thermoelastic martensitictransformation”. Below the transformation temperature, Nitinol ismartensitic. The soft martensitic microstructure is characterized by“self-accommodating twins”, a zigzag like arrangement. Martensite iseasily deformed by de-twinning. Heating the material converts thematerial to its high strength, austenitic condition. The transformationfrom austenite to martensite (cooling) and the reverse cycle frommartensite to austenite (heating) do not occur at the same temperature.There is a hysteresis curve for every Nitinol alloy that defines thecomplete transformation cycle. The shape memory effect is repeatable andcan typically result in up to 8% strain recovery.

SUPERELASTICITY: Martensite in Nitinol can be stress induced if stressis applied in the temperature range above Af (austenite finishtemperature). Less energy is needed to stress-induce and deformmartensite than to deform the austenite by conventional mechanisms. Upto 8% strain can be typically accommodated by this process. Sinceaustenite is the stable phase at this temperature under no-loadconditions, the material springs back to its original shape when thestress is removed. This extraordinary elasticity is also called“pseudoelasticity” or transformational “superelasticity”. The typicalstress-strain curve of a properly processed Nitinol alloy shows theloading and unloading plateaus, recoverable strain available, and thedependence of the loading plateau on the ambient temperature as is wellknown in the art. The loading plateau increases with the ambienttemperature. As the material warms above the austenite finishtemperature, the distinctive superelastic “flag” curve is evident. Uponcooling, the material displays less elasticity and more deformationuntil it is cooled to where it is fully martensite; hence, exhibitingthe shape memory property and recovering its deformation upon heating.Nitinol alloys are superelastic in a temperature range of approximately50 degrees above the austenite finish temperature. Alloy composition,material processing, and ambient temperature greatly effect thesuperelastic properties of the material. For medical devices binaryNitinol alloys, when processed correctly, are at their optimumsuperelastic behavior at body temperature.

Nitinol Devices & Components manufactures binary Nitinol materials withAf's ranging from −15 degrees centigrade to +100 degrees centigrade forboth superelastic and shape memory applications.

Smart memory materials can also be metallic alloys of copper, zinc andaluminum or iron, nickel and aluminum, and the like.

Many modifications and variations of the present invention are possiblein light of the above teachings. Therefore, it is to be understood thatwithin the scope of the appended claims, the inventions may be practicedotherwise than as specifically described. For example, numerousmechanisms may be available for articulating and modifying the size andconfiguration of the surgical device. Moreover, the reference numeralsare merely for convenience and are not intended to be in any waylimiting. Similarly, the components of the invention can be arrangedrelative to one another in a variety of configurations other than thoseshown.

1. A surgical device for cutting a portion of a body comprising: a knifecapable of moving from a first position to a second position which isspaced apart from the first position; a smart memory material (SMM)capable of going from one physical state to another physical state; andan activating apparatus which is in communication with the smart memorymaterial and which can cause the change in the physical state of thesmart memory material, which change in state causes the movement of theknife thereby facilitating cutting of the desired body portion.
 2. Thesurgical device of claim 1 wherein the SMM is a metallic alloy.
 3. Thesurgical device of claim 1 wherein the SMM is a polymeric material. 4.The surgical device of claim 1 wherein the activating apparatus is asource of electricity which when activated causes the SMM to expand involume thereby moving the knife.
 5. The surgical device of claim 1wherein the activating apparatus causes the SMM to expand in volumethereby moving the knife.
 6. The surgical device of claim 1 wherein theSMM is a metallic alloy comprised of a composition, which can go from amartensite phase to an austenite phase.
 7. The surgical device of claim1 wherein the SMM is a metallic alloy comprised of nickel and titanium.8. The surgical device of claim 1 wherein the SMM is a metallic alloy ofcopper, zinc and aluminum or iron, nickel and aluminum.
 9. A method ofcutting a body portion comprising: providing the device of claim 1; andcutting the desired body portion.